1. Display all files or directories with L, ending with a lowercase letter, and with at least one digit in the middle of the/var directory
2. display files or directories that start with any digit in the/etc directory and end with a non-digit
3, display/etc/directory with a non-letter beginning, followed by a letter and any other arbitrary length of any character file or directory
4. Display all the numbers in the/etc/directory starting with RC, followed by 0-6, other files or directories of any character
5. Display all files or directories ending with. D in the/etc directory
6. Display the files or directories with the end of. conf and beginning with m,n,r,p in the/etc directory
7. Show only hidden files and directories under/root
8. Show only non-hidden directories under/etc
9. Display the file or directory of any three-digit name in the/proc directory
10. Display all files or directories that start with K, end with a lowercase letter, and have at least one digit in the middle of the/etc directory
11. Display all files or directories starting with M and ending with a number and x in the/usr/share/man directory
12. Displays all files or directories that start with a capital letter and end with two digits in the/etc directory
13. display files or directories with a file name containing at least one lowercase letter and one number and ending with. conf in the/etc directory
14. Show only non-hidden directories under User's home directory
15, define the alias command baketc, the/etc/directory of all files, backup to/testdir separate subdirectories, and request
subdirectory format is BACKUPYYYY-MM-DD, the backup process is visible (one command)
16. display files or directories with symbols and numbers in the/var/log directory (to be solved)
The fan usage of Linux ls
